“Forever Plaid,” like “Greater Tuna” and “Nunsense,” is one of those theatrical surprises that not only takes off on its own, but spawns a series of related shows as well â€¦ all of which make big money in return for a patently silly night out.

Capital Repertory Theatre is offering “Plaid Tidings” as its holiday show this season, and if you happened to miss the original “Forever Plaid,” not to worry.

The first few minutes of the first act of “Tidings” will quickly bring you up to speed on Frankie, Smudge, Jinx and Sparky â€¦ the four lads who died in a crash with a bus full of Catholic schoolgirls while on their way to see The Beatles on “The Ed Sullivan Show.”

In “Forever Plaid,” the boys get to perform the concert they were denied in life; in “Tidings” they put on the holiday show that never was.

Basically, “Tidings” is a night of nifty harmony singing interwoven with old-fashioned comedy shtick that would have seemed at home on, say, “Sullivan” or “The Perry Como Show,” both of which are well-represented here.

A barrage of tunes â€¦ some holiday, some not â€¦ are thrown at lucky listeners, often in deliberately chaotic medleys that impress as much from the angle of inventive arrangements as from sheer vocal calisthenics.

Capital Rep’s cast is largely made up of ringers who have had experience with the show, including Dale Sandish, who directs, choreographs and plays the role of Sparky, the joker of the bunch.

Mark Perkins plays Frankie, and nearly steals the show with a solo rendition of “Rudolph the Red-Nosed Reindeer” that devolves into a psychological deconstruction of the song â€¦ “and don’t even get me started on “Frosty the Snowman!”

Christopher Youngsman plays the nerdy Smudge, and Ric Ryder completes the quartet as the inept and aptly-named Jinx.

At Capital Rep the gents are accompanied by Randy Glass on piano and Michael Wicks on bass, and work out their routines on a lovely set designed by Dana Kenn.

There are plenty of fun numbers in the show. The best include a “Sh-Boom” delivered with plumber’s helpers; a crazed “Besame Mucho” from Ryder; and a classic bell routine (including “Joy To The World” and “Mr. Sandman”) that puts a volunteer from the audience (a plaid-clad Carol on Wednesday’s opening night) on the spot.

The “Sullivan” bit, which condenses an entire program into three minutes is also sheer comic pandemonium that must be seen to be believed.

No surprise here that the critic will end with a sentence claiming that “Plaid Tidings” is not exactly an intellectual’s night out, but just a lighthearted bit of holiday fluff.

And that’s just what it’s meant to be.

Michael Eck, a freelance writer from Albany, is a regular contributor to the Times Union.